In ArF immersion lithography and extreme ultraviolet light (EUV) lithography, shrinkage of processing dimension of a resist line has been required. In the formation of a finer resist pattern as described above, when a contact area between the resist pattern and an underlying substrate decreases, an aspect ratio of the resist pattern (height of the resist pattern/line width of the resist pattern) increases. Thus, there is a concern that the resist pattern is likely to collapse. Therefore, for a resist underlayer film (anti-reflective coating) that contacts a resist, high adhesion to the resist has been required such that the collapse of the resist pattern does not occur.
It has reported that when a lactone structure is used as a component of a resist underlayer film-forming composition to exhibit high adhesion to the resist in the resist underlayer film, the adhesion to a resist pattern to be obtained is enhanced (Patent Document 1). Therefore, when a structure containing a polar moiety like the lactone structure is used as the component of the resist underlayer film-forming composition, the adhesion to the resist pattern is enhanced. Accordingly, prevention of collapse of the resist pattern in the finer resist pattern has been expected.
However, in a lithography process that requires the formation of the finer resist pattern, such as ArF immersion lithography and extreme ultraviolet light (EUV) lithography, only the lactone structure that is the component of the resist underlayer film-forming composition cannot sufficiently prevent the collapse of the resist pattern.
On the other hand, examples of procedures of exhibiting high adhesion to the resist include a method for controlling a chemical state of an interface between the resist and the resist underlayer film. Patent Document 2 describes an additive for a resist underlayer film-forming composition that can suppress conversion of a resist pattern shape into an undercut shape by modifying a surface state of a resist underlayer film into a basic state.